Magnetic Random Access Memory (“MRAM”) is a non-volatile memory. MRAM devices may perform read and write operations faster than conventional long term storage devices such as hard drives. In addition, MRAM devices may be more compact and may consume less power than conventional storage devices.
A typical MRAM device includes an array of memory cells in which word lines extend along rows of the memory cells and bit lines extend along columns of the memory cells. Each memory cell is typically located at a cross point of a word line and a bit line.
A memory cell in an MRAM device stores a bit of information according to an orientation of a magnetization of layer within the MRAM device. The magnetization of a memory cell assumes one of two stable orientations at a given time. The two orientations are typically referred to as parallel and anti-parallel and represent logic level values of ‘0’ and ‘1’, respectively.
The magnetization orientation affects the resistance of the memory cell such as a spin dependent tunneling junction device. For instance, the resistance of a memory cell is a first value if the magnetization orientation is parallel, the resistance of the memory cell is increased to a second value if the magnetization orientation changed from parallel to anti-parallel. The magnetization orientation of a selected memory cell, and therefore the logic state of the memory cell, may be read by determining the resistance state of the selected memory cell.
One of the challenges with MRAM devices involves electrically isolating the circuits that comprise the memory cells while maintaining a sufficient level of packing density. Although additional components such as transistors may be used to increase the isolation of memory cells, an increase in the number of components typically results in a decrease in the packing density of the memory cells, i.e., the number of memory cells per a given area, and a decrease in the packing density generally results in increased costs.
It is desirable to be able to increase packing densities while increasing the electrical isolation of memory cells. It is also desirable to maintain reliability of sensing states of the memory cells.